The Mesozoic followed on the heels of two mass extinctions which wiped out approximately 90% of foraminiferal genera. Most larger benthic foraminifera disappeared (ie. Fusulinina), however, smaller, simpler forms (i.e., Textulariina) only lost about 30% of total genera.

The Triassic larger foraminifera have not been systematically studied on a global scale like the Permian forams have. Rettori (1995) presents a revised taxonomoy of the Early and Middle Triassic taxa and Pybernes in De Gracianski et al (1988) presents a stratigraphic summary of forams in the Tethyan realm. Please refer to these as well as Chapter 3 of BouDagher-Fadel (2008) for more information and detail of the taxonomy during this geologic period. Here, we present a brief summary and morphological classification of the genera characteristic of the Triassic, compiled predominantly from BouDagher-Fadel (2008).

The Triassic large benthic foraminifera are developed in five suborders (Textulariina, Fusulinina, Involutinina, Miliolina, Lagenina). The development and evolution of the superfamilies of these suborders is shown in the figure to the left. Most of the Triassic forams are relatively morphologically small, although they are distinguishable in thin section so are identified as "larger benthic foraminifera".

Wall: microgranular without optical alignment; advanced forms have two or more differentiated layers in the wall

Geologic range: Silurian to Late Triassic

Superfamily EARLANDIOIDEA

Test: free, non-septate with a globular first chamber and a straight tubular second one

Geologic range: Late Silurian to Early Triassic

Family Earlandiidae

Chamber: single, free

Geologic range: Late Silurian to Early Triassic

Earlandia

Test: free, elongate, composed of a globular proloculus followed by an undivided straight tubular chamber

Wall: calcareous, microgranular

Geologic range: Late Silurian to Early Triassic

Superfamily ENDOTHYROIDEA

Test: streptospiral to planispiral with many chambers, followed by a rectiniliear stage, which is biserial or uniserial in some forms

Wall: microgranular, calcareous, but some forms show two to three distinct layers; others may develop an inner perforate or keriothecal layer

Geologic range: Late Devonian to Triassic

Family Endotebidae

Test: free planispiral in early stages, later uniserial to biserial

Wall: calcareous agglutinated, grey, thick with simple aperture

Geologic range: Late Permian to Triassic

Genera: Endoteba, Endotebanella

Family Endotriadidae

Test: trochospiral almost planispiral, may be uniserial in later stages with a microgranular wall and basal, simple aperture

Geologic range: Middle to Late Triassic

Genera: Endotriada, Endotriadella

The figure to the left below depicts the evolutionary path of the Endotebidae from the Endothyridae (Earlandia) (Vachard et al., 1994). The endoteba has a compressed axial view and the endotebanella is similar but the final stage is uniserial. The endotriada has hemispherical chambers while the endotriadella is uniserial.

SUBORDER INVOLUTININA

Test: All forms of this suborder have an enrolled second chamber with an aragonitic but commonly recrystallized wall to give a homogenous microgranular structure. The umbilical region has pillar-like structures on one or both sides of the test.

Geologic range: Early Permian to Late Cretaceous

The figure above depicts the evolutionary lineages of the main genera of the Involutinina (BouDagher-Fadel, 2008)

Superfamily INVOLUTINOIDEA

Test: a first chamber followed by a planispiral to trochospiral enrolled tubular second chamber

Geologic range: Early Permian to Late Cretaceous

Family Triadodiscidae

Test: the umbilical area is covered with additional lamellae added with each new whorl

Geologic range: Early to Late Triassic

Triadodiscus

Test: lenticular with globular proloculus followed by a planispiral to slightly trochospiral and involute second undivided tubular chamber that is planispiral. Whorls are formed by a single lamella

Geologic range: Triassic

Family Aulotortidae

Test: lenticular to conical with calcareous imperforate walls, consisting of a globular prolocular followed by a tubular enrolled and undivided second chamber, lying against the previous whorl to form planispiral, oscillating or trochospiral coiling. Each half whorl is followed by the lamellar deposition of one or two layers

Aperture: at the open end of the tubular chamber

Geologic range: Triassic to Middle Jurassic

Auloconus

Test: The second chamber is a trochospirally enrolled tubular chamber. Each half whorl forms a lumina, which covers the umbilicus resulting in

the build up of a thick and solid umbilical filling.

Geologic range: Triassic

Aulotortus

Test: The enrolled second chamber is planispiral to slightly streptospiral, oscillating around the proloculus.

Geologic range: Triassic to Middle Jurassic

Family Triasinidae

Test: with proloculus followed by a broad tubular chamber. The interior is filled wth cylindrical pillars

Geologic range: Triassic

Genera: Triasina

Family Involutinidae

Test: globular proloculus followed by a trochospiral coiled tubular second chamber with secondary lamellar thcikenings on one or both umbilical regions

Aperture: at the open end of the tube

Geologic range: Triassic to Late Cretaceous

Genera: Involutina; Semiinvoluta; Trocholina

Involutinina

Test: Both umbilical regions are filled with lamellar deposits.

Geologic range: Triassic to Late Cretaceous

SUBORDER MILIOLINA

Test: porcelaneous and imperforate, made of high-magnesium calcite with fine, randomly oriented crystals

Geologic range: Carboniferous to Holocene

The evolution of the Triassic miliolines from a Permian ancestor (modified from Zaninetti et al, 1991; Rettori, 1995; BouDagher-Fadel, 2008).

Superfamily CORNUSPIROIDEA

Test: free or attached, and composed of a globular proloculus followed by a tubular enrolled chamber. Coiling is planispiral or trochospiral, evolute or involute and may become irregular

Aperture: simple and at the end of the tube

Geologic range: Early Carboniferous to Holocene

Family Arenovidalinidae

Test: lenticular with a globular proloculus and a second undivided chamber

Geologic range: Early to Middle Triassic

Genera: Arenovidalina; Paratriasina

Family Ophthalmidiidea

Test: free, composed of a proloculus followed by an undivided coiled second chamber and chambers that commonly are one-half coiil in length

Wall: porcelaneous

Aperture: terminal and simple

Geologic range: Triassic to Holocene

Eoophalmidium

Test: Involute coiling

Geologic range: Anisian

Karaburunia

Test: The proloculus is followed by sigmoidal coiling of two chambers per whorl, the final pair of chambers are approximately 180 deg. apart.

Geologic range: Triassic (Late Anisian)

Family Meandrospiridae

Test: composed of a proloculus and an undivided second chamber with zigzag coiling

Aperture: simple and terminal

Geologic range: Permian to Holocene

Genera: Meandrospira; Meandrospiranella; Turriglomina

Family Cornuspiridae

Test: free or attached, composed of a proloculus followed by an undivided planispiral to streptospiral, involute or evolute second tubular chamber

Geologic range: Early Carboniferous to Holocene

Genera: Planiinvoluta

Family Hemigordiopsidae

Test: at least an early streptospiral stage, that later may be planispiral.

Geologic range: Early Carboniferous to Holocene

Genera: Agathammina

Family Hoynellidae

Test: free, with a globular proloculus followed by an early miliolid stage and an undivided tubular chamber arranged on several vertical planes

Geologic range: Triassic to Early Jurassic

Genera: Hoynella

SUPERFAMILY SORITOIDEA

Test: chambers are planispiral, uncoiling, flabelliform or cyclical, and may be subdivided by partitions or pillars

Geologic range: Late Permian to Holocene

Family Milioliporidae

Test: free or attached with a proloculus and tubular chambers arranged in various planes of coiling which may be irregular, oscillating or sigmoidal

Geologic range: Late Permian to Late Triassic

Genera: Galeanella; Kamurana

SUBORDER LAGENINA

Wall: monolamellar, composed of low-magnesium calcite in which the optical c-axes of the crystal units are perpendicular to the outer surface of the test. Primitive taxa are without secondary lamination, but more advanced forms are found with secondary lamination and a thin microgranular inner layer

Geologic range: Late Silurian to Holocene

Superfamily DUOSTOMINOIDEA

Test: enrolled, planispiral to trochospiral

Aperture: single or double, interiomarginal

Geologic range: Triassic to Early Jurassic

Family Duostominidae

Aperture: two interiomarginal in the final chamber

Geologic range: Triassic

Duostomina

Test: lenticular, trochospirally coiled

Geologic range: Triassic

Superfamily GEINITZINOIDEA

Test: uniserial, similar to the Nodosinelloidea but the microgranular layer is the